Thanksgiving food is a link to the past, a thing to be grateful for, and a way to keep your extended family from talking to you about politics or religion. But it has a weirder, wilder side to it. Here are 10 things you didn’t know about your favorite Thanksgiving dishes.

10) Sweet Potatoes Were Henry VIII’s Favorite Aphrodisiac

Many foods have been considered aphrodisiacs, but sweet potatoes were more famous than most for “procuring bodily lust.” Their powers are mentioned by no less a poet than Shakespeare, who writes in The Merry Wives of Windsor, “Let the sky rain potatoes; let it thunder to the tune of ‘Green Sleeves’; hail kissing-comfits and snow eringoes; let there come a tempest of provocation, I shelter me here.” Today they’re a staple of upscale burger joints, but at the time they were a new food from an exotic land, introduced into a culture hungering for sweetness. We know that Henry VIII liked sweet potatoes, and probably would have had them either boiled with prunes or made into what we would now consider to be a spiced sweet potato pie.

9) Thank the French for Both Independence and Pumpkin Pie

Pumpkins are a new world food. They are one of the few foods that might have figured prominently in the pilgrim’s diet, especially during celebrations. However, the earliest pumpkin pies were more like pumpkin puddings. Pumpkin flesh was cooked in the shell, occasionally with milk and spices.

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That in 1651 changed when a French chef called Francois Pierre la Varenne wrote a cookbook called Le Vrai Cuisinier Françoise. In it he featured a recipe that recommending boiling pumpkin pulp with milk, straining it, and then mixing it with sugar, butter, and salt. The cook finished up by baking it in a pastry shell. Merci!

8) Freeze-Dried Potatoes Have Been Around Since the 1400s

Today is probably not the day you’ll make potatoes from freeze-dried flakes, but if you did you’d be participating in a true American tradition—albeit a South American tradition. The Inca were the first to freeze dry potatoes. They got geographical help with the process, since the Andes allow for freezing temperatures at night and scorching heat that evaporates the moisture from the potatoes during the day. The people, though, developed a multi-day process for freeze-drying potatoes (including walking on them to remove both skins and dew), and made huge storage facilities so they could enjoy potatoes year-round.

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If you’re making regular mashed potatoes on Thanksgiving, be sure to use a hand-held masher and stay away from blenders and food processors. Mashing potatoes is supposed to separate most of the cells and break just enough of them to release enough starch to keep the potatoes together. Blending will release too much starch and make the potatoes gluey.

7) Cranberries Can Prevent the Formation of Bacterial Biofilms

Cranberry juice is famous for helping people fight urinary tract infections. If you’ve ever had one, there’s a 90% chance it was caused by the celebrity bacteria, E. coli, as that is what’s responsible for nine out of ten of what scientists tactfully refer to as “community-acquired UTIs.” Cranberry juice helps, but only recently have scientists figured out exactly how it helps.

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Since it would be unethical to infect people with E. coli, or leave them untreated if they were already infected, scientists restricted themselves to collecting the urine from uninfected people. Some of those people were asked to drink a lot of water, and some were asked to drink cranberry juice. When exposed to urine filled with cranberry juice, the E. coli bacteria suddenly became less able to stick to each other or anything else. This loss of adhesion meant they couldn’t get together and form biofilms, slick sheets of bacteria that foster further growth. Cranberries don’t kill bacteria directly, but they do run bacterial social clubs out of town.

6) Stove Top Stuffing Was a Scientific Endeavor

If you like instant stuffing, you can thank Ruth Siems. Fresh stuffing is fairly resilient. It can be soaked in turkey goo or jammed into a pan and cooked like a poundcake or fried up on the stove before being heated all over in the oven or microwave. Dried stuffing is delicate. It has to be re-hydrated, which means that its inventors had to find just the right size to the bread crumbs.

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For a while, adding liquid to the breadcrumbs soaked them through, and left them with the texture of wet tissue paper at the end of the cooking process. Making the breadcrumbs bigger, or making them the wrong shape, left the centers dried and rock hard. Ruth Siems led the team that eventually got the crumbs the right size and shape to bake up soft and fluffy.

Then the ashes started to do something. Ashes from the fire were often saved and boiled with potassium salts. The resulting white mixture could be made into soap or other cleaning agents. Cooks found that, when they were making sourdough, they could cut the sour taste by adding a little “potash” to the bread. Then they found that the bread made with potash rose more quickly.

Up until then, the only way to make bread rise was to add some yeast. Even cakes were yeast-based. Anything that didn’t rise with yeast didn’t rise at all. Potash was a quick way to fix that. By the 1800s, cooks all over America were turning into chemists, mixing potash and acids in their cornbread to make it rise. The risen dough had a bitter taste, so they added sweeteners. Cornbread stopped being what you ate when you couldn’t get anything else and became more of a treat. Eventually, homemade potash was replaced by commercially-made baking soda, giving us the slightly sweet, fluffy cornbread we eat today.

4) Marshmallow Yam Topping Started a Marshmallow War

The barrel-shaped marshmallows in bags that you see in the stores today are not like the marshmallows of old. For the most part, marshmallows used to be square. Homemade marshmallows are poured out into a large dish, left to solidify, and then cut into squares like brownies. Companies extruded them from a machine instead, but they kept the homemade feel, and they sold marshmallows in packets or tins.

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In 1917, to boost sales, Angelus Marshmallows decided to promote their marshmallows by including a recipe book on how to cook with them. Few of the recipes caught on, which is why we don’t have marshmallow omelets today, but marshmallows did catch on as an way to make cocoa better and as a very special topping for yams.

The sales of Angelus Marshmallows went up so fast that a competing company, Campfire Marshmallows decided to fight back. It not only also promoted marshmallow recipes (like jellies with marshmallow topping), it made practical changes to its packages. Cooks needed more marshmallows and the square shape wasn’t always attractive, so Campfire made their marshmallows round and sold them in big bags. Others followed suit, which is how candied yams launched the modern marshmallow.

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3) Your Gravy Serves a Nutritional Purpose (and It Needs Soy Sauce)

The Royal Society of Chemistry caused a stir in 2009 when it released a general recipe for perfect gravy which included soy sauce. The soy sauce was meant to add MSG, which would improve the savory flavor of the gravy. The recipe caused shock and outrage, but also a lot of publicity for the RSC, making them scientific shock jocks.

For what it’s worth, the RSC also pointed out the importance of gravy. A lot of nutrition seeps away with the juices of roasted meat, including proteins, folic acid, and vitamins B1 and B6. Gravy, made from those juices, is a tasty way to get them back into the system.

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As for the recipe, perhaps the RSC felt some backlash, because it’s hard to find online. Here is a basic description. For those of you contemplating adding soy sauce to your gravy, be aware that they mostly tested this out on beef gravy. And that they describe it positively as “marmite-like.”

2) Green Bean Casserole Got Its Inventor Into the Hall of Fame

When you fix your polite smile on your face and reluctantly bite into a green bean casserole this Thanksgiving, you will be celebrating the 60th anniversary of this most dreaded of Thanksgiving foods. It was invented in 1955, by Dorcas Reilly, an employee at the Campbell’s Soup Company.

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While no one really enjoys its taste, we can at least pay tribute to the casserole as a marvel of practicality. Reilly wanted something that would be fast to make, involve ingredients that most people would already have in their kitchens, and that could be made ahead of time and reheated by the busy cook. She had to use Campbell’s Soup, and she picked cream of mushroom. To that she added milk, soy sauce, and a bag of frozen green beans. The dish didn’t look appealing, so she sprinkled the top with fried onions. For this culinary masterpiece, she was inducted into the Inventor’s Hall of Fame, wherethe original recipe card is forever preserved there.

1) Turkey Makes Urine Turn Purple

Purple urine isn’t great, but to be fair to turkey, it might be seen more as a useful diagnostic tool than a problem. Purple urine is a sign that a person has a bacterial infection.

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It starts with tryptophan, which is found in turkey. The chemical does no harm, and as it goes through the digestive system is naturally broken down into indoxyl sulfate. If it has to go stay in the digestive system for a while, bacteria get at it and further break it down into indoxyl. Bacteria can turn urine alkaline. In an alkaline environment, the indoxyl turns into indirubin and indigo. When the urine comes out, especially if it comes out of a patient in a hospital who is catheterized, it can turn green, blue, or sometimes a deep purple. The condition has come to be known as Purple Urine Bag Syndrome. That’s one way to enliven Thanksgiving.